This paper describes design optimization and performances of hybrid optical transmission lines consisting of effective-area-enlarged pure silica core fiber and dispersion compensating fiber. As a result of the design optimization, considering low nonlinearity and good bending characteristic, the developed fibers exhibit a span average loss of 0.208 dB/km, a span average dispersion slope of 0.02 ps/nm2/km and low nonlinearity with an equivalent effective area of 60 µm2. Further optimization of the relationship among the nonlinearity, the dispersion slope and the bending characteristic enables perfectly dispersion-flattened hybrid optical transmission lines exhibiting a low transmission loss of 0.211 dB/km, low nonlinearity with an equivalent effective area of 60 µm2 and small dispersion deviation of 0.03 ps/nm/km in a wavelength band wider than 40 nm.